Growth and physical properties of CdS thin films prepared by chemical bath deposition

Abstract

This work deals with the preparation of cadmium sulfide (CdS) thin films by chemical bath deposition. The influence of the solution temperature is investigated in this study. We suggest that activation energy of the deposition rate measurement can be a tool for determining the nature of the deposition mechanism. We found that at low solution temperature, the growth mechanism proceeds via the ion by ion process, and found the corresponding activation energy equal to 0.06 eV. However, at higher solution temperature, the film deposition became via the cluster by cluster process, the growth rate activation energy is equal to 0.48 eV. The films' structural and optical properties were studied by x-ray diffraction analysis and UV–visible spectrophotometry. Structural analysis revealed that the deposited films have a cubic structure, and the crystallite size decreases with increasing deposition temperature. The transmission spectra of the film, in the visible range, show a high transmission coefficient (70%). The transmittance data analysis indicates that the optical band gap is closely related to the solution temperature. From this analysis, a direct band gap ranging from 2.21 to 2.34 eV was deduced. From the electrical characterization we inferred that CdS films are n-type and their dark conductivities reduced with increasing bath solution temperature. From the photoconductivity measurements we concluded that films deposited at low temperatures (less than 60 °C) or high temperatures (higher than 70 °C) have good optoelectronic properties suitable for utilization as a buffer layer in thin film solar cells.

Electrodeposition and Characterization of Cu(In, Al)Se<sub>2</sub> for Applications in Thin Film Tandem Solar Cells

“…As can be seen, the variation of the band gap energy is opposite to the Urbach energy, similar observations have been reported by earlier workers [22].…”

Chemical bath deposition of CdS films on different substrate orientations

“…The growth mechanism of CdS films can be explained by ion by ion (heterogeneous reaction) or by cluster by cluster (homogeneous reaction), but not enough evidence exist to distinguished them with our results. The activation energy during deposition needs to be obtained to explain the growth mechanism [21].…”

Channel length specific broadspectral photosensitivity of robust chemically grown CdS photodetector

“…However, solution based techniques are more economical and efficient for large scale production of nano film based photodetectors. 5 Chemical bath deposition (CBD) [6][7][8][9][10][11][12][13][14][15][16][17] is the most commonly used technique to make CdS thin films and have been studied heavily for their photodynamics, electro-optical studies and also known low cost material for photodetector applications. One of the big advantages of CBD method is that film can be made over a large area (mm 2 ).…”